Conveyors are used extensively to transport materials, such as sand, gravel and coal, from one location to another. Continuous conveyor belts are often used to efficiently, effectively, and continuously transport material. It is a problem that with continuous conveyor belts that material often adheres to the conveyor belt, due to moisture and other conditions, after the material has passed the intended delivery point. Material that remains on the belt can interfere with the proper functioning of the conveyor system by way of increased wear and tear on the conveyor belt and damage to the rollers supporting the belt on the return section of the continuous loop.
Several devices disclose the use of scraper blades to remove materials that have adhered to the conveyor belt. These devices are effective for a period of time, but only with frequent adjustments or tensioning throughout the entire wear life of the scraper blades. Scraper blades tend to wear over time; typically, in one to one and a half years, the scraper blades need to be replaced. As the scraper blades wear down, several phenomena occur. Firstly, the surface area of the blade that is in contact with the conveyor belt increases as the blade wears. Secondly, the biasing force of the support arm of the blade against the belt diminishes over time, thereby causing insufficient biasing of the blade against the belt. Thirdly, the arm that biases the blades against the belt must be adjusted so as to enable the blades to exert sufficient force against the belt as the blade wears. Otherwise, the blades do not remain biased against the conveyor belt with sufficient force to permit the effective scraping of material from the belt. Typically, the support arm is adjusted manually to bias the blade against the belt. Manual adjustment of the support arm requires shutting down the conveyor line. As the blades wear, more frequent adjustment of the support arm is necessary. As one can readily appreciate, frequent intermittent manual adjustment of the arm results in downtime and efficiencies. Moreover, even frequent adjustment of the support arm does not adequately compensate for the continuous wearing of the blades.
Thus, a tensioner is needed to overcome the continuous loss of biasing force such that the biasing force of the arm and blade against the belt remains sufficient, as the blade(s) wear, so as to permit effective cleaning of the belt. Also needed is a tensioner with a useful life at least as long as the useful life of the scraper blade(s). Further, a self-adjusting tensioner is needed which compensates for the wearing of the scraper blade and corresponding loss of biasing force in the arm and blade, with virtually no manual adjustment of the support arm, such that the use of the scraper and tensioner remains substantially uninterrupted.